IL108004A

IL108004A - Infusion system automatic safety closure valve

Info

Publication number: IL108004A
Application number: IL10800493A
Authority: IL
Original assignee: Travenol Lab Israel Ltd
Priority date: 1993-12-13
Filing date: 1993-12-13
Publication date: 1999-07-14
Also published as: IL108004A0

Description

n inj'N rcnyi¾"D 'jintn 'ΙΛΏΊΙΠΚ ητ ΧΌ ainouj INFUSION SYSTEM AUTOMATIC SAFETY CLOSURE VALVE SWI BARAK C:0618 0618i nf . va 1 EL-33 12.12.93 INFUSION SYSTEM AUTOMATIC SAFETY CLOSURE VALVE FIELD OF THE INVENTION The present invention relates to medical instruments and devices for providing intravenous infusion, and more particularly, to an automatic safety closure valve for medical infusion sets which are used with infusion pumps.

BACKGROUND OF THE INVENTION Two major methods are known for providing for intravenous infusion of medical fluids to a patient. One system uses an infusion pump known as an electronic infusion device (EID), which accounts for about 20% of the applications. The older, more common approach uses a gravity flow method, accounting for 80% of the applications, in which the gravitational force causes fluid in a container (bottle or bag) to flow to the patient's body through plastic tubes known as an infusion set, or an IV administration set.

In the latter, more common method, regulation of the flow rate is performed via a roller clamp which is connected as a standard device in each infusion set. This method is utilized in situations where accuracy is not essential, since the fluctuations in this method can range within hundreds of percent, since establishing a flow rate via a roller clamp is not accurate and during the infusion procedure the fluid flow rate can change.

The more advanced method of administering infusion uses an infusion pump (EID), and this method must be accurate, within +/- 5% of a desired flow rate, since the medical treatment is planned in accordance with the desired rate. While using this method, the roller clamp is not in use. The general instructions provided by each pump manufacturer indicate that the roller clamp is to be opened completely after inserting the tubing in the pump and closing the pump door. The door of the pump stops free-flow of fluid even when the pump is turned off.

A serious problem presented by the use of IV infusion pumps occurs in the case where a nurse, or in many cases other untrained personnel, deliberately turns off the EID and removes the infusion set from the pump to facilitate patient movement, and as a result, free-flow (gravitational) of the medicinal fluid is established. Such incidents may be hazardous or even fatal depending on the medication and the patient's condition.

Most infusion pumps have devices installed which prevent free-flow of medicinal fluid in the situation where the door of the pump is opened in an involuntary fashion. But not all infusion pump manufacturers have installed such devices. Many manufacturers have left the problem to fate, with the hope that the nurse will always remember to close the roller clamp before opening the pump door, or that there will never be a situation in which the pump door has been opened involuntarily.

After investigation of the problem in the US, medical authorities have concluded that despite the fact that pump manufacturers have installed protective devices as described, these are not foolproof, since sometimes the nurse removes the IV set from the pump without closing the roller clamp.

Thus, an urgent need has been created for manufacture 108004 /2 of IV infusion sets having an automatic closure, which stops the fluid flow if by accident the user forgets to close the roller clamp. In other words, a device is needed to provide a 100% guarantee that when the IV set is removed from the pump, there cannot be a free-flow situation as a result of user error.

In the gravity flow system, such a situation does not occur, since there is no pump and the nurse manipulates the roller clamp to set the desired rate. If the infusion is to be interrupted, the roller clamp will be closed. However, where the infusion pump is used, turning off the pump stops the pump operation but does not stop the free-flow of the fluid if the IV infusion set was removed from the pump.

Many manufacturers have installed protective devices in their new instruments, but since these protective devices are adaptable only to the latest models of their own pumps, a dangerous safety gap exists between the newer and older models.

It would therefore be desirable to provide an automatic safety closure valve which is adaptable to existing IV sets, to prevent free-flow of fluid where infusion pumps are used.

U.S. Patent 5,211,201 describes an air elimination system for intravenous fluid delivery comprising a valve and a control means operative to permit or deny fluid flow through the valve in response to the presence or absence of air in the fluid stream. U.S. Patent No. 5, 158, , 539 discloses a one-way valve intended for a heart-lung machine. U.S. Patent No. 4, 346,, 704 discloses an elastomeric valve which lacks manual operation, and U.S. Patent No. 4,895,346 discloses an elastic catheter seal, not a valve.

SUMMARY OF THE INVENTION Accordingly, it is a principal object of the present invention, to overcome the above-mentioned hazards of prior art infusion systems and provide an automatic safety closure valve which can be applied universally to infusion pumps and systems.

In accordance with a preferred embodiment of the invention, there is provided, in a medical infusion system, an automatic safety closure valve comprising: means for connecting together at least two tubes for conducting fluids; and valve means associated with said connecting means. characterised in that said valve means prevents free-flow of fluid therethrough below a predetermined fluid pressure.

Preferably the predetermined flow pressure is greater than that developed by gravity flow of fluid in the infusion system, and an exemplary value is in the region of 140mm mercury. Preferably the valve means allows free flow of fluid therethrough when the predetermined fluid pressure is exceeded.

In a preferred embodiment, the automatic safety closure valve is provided as a rigid nozzle protruding from a connector joining two infusion tubes of larger and smaller diameters. The rigid nozzle is formed with four holes or slits located about its circumference, and an elastic sleeve is placed over the nozzle. When the infusion pump establishes a pulsed flow with a sufficient fluid pressure, the automatic safety closure valve allows freeflow of the fluid therethrough. If the pressure falls below this level, the valve closes and fluid flow ceases.

The elastic sleeve may be of latex, silicone, flexible PVC, or any other suitable material. Thus manipulation of the valve means distorts its shape and enables free flow of liquid therethrough.

Prior to use of IV infusion set, it must be primed by allowing air to exit the tubes and be replaced by fluid, and the inventive valve is shaped so that when squeezed, the sleeve becomes distorted and free-flow of fluid is allowed.

According to a further aspect of the invention there is provided a method of furnishing an automatic safety closure valve for a medical infusion system comprising the steps of: connecting together at least two tubes for conducting fluids; and providing valve means associated with said connecting means for preventing free-flow of fluid therethrough below a predetermined fluid pressure.

An advantage of the inventive design is that it is not affected by the type of infusion system utilized and can be universally installed and adapted to any pump or infusion set. In addition, its small size can be integrated into any infusion set, such as a standard infusion tubing diameter (3.1 x 4 mm).

Other features and advantages of the invention will become apparent from the following drawings and description.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention with regard to the embodiments thereof, reference is made to the accompanying drawings, in which like numerals designate corresponding sections or elements throughout, and in which: Fig. 1 is an overall view showing components of a medical infusion system, for use with an inventive closure valve; Fig. 2 is a cross-sectional side view of a preferred embodiment of an automatic safety closure valve constructed and operable with an infusion set in accordance with the principles of the present invention; Figs. 3-5 are front end views of the automatic safety clos.re valve of Fig. 2, respectively, before assembly of the valve with an elastic sleeve, after assembly of the sleeve and during operation; Fig. 6 is a side view of an alternative embodiment of of the present invention, featuring a modified connector for the automatic safety closure valve in an infusion set; and Fig. 7 is a side view of the modified connector assembled with the infusion set.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to Fig. 1, there are shown the overall components of a medical infusion system 10 comprising a IV drip bag 12 containing the medication for infusion, a transparent drip chamber 14, a manual roller clamp 16 for adjusting the flow rate, and an electronic infusion pUmp 18. The system components are connected by flexible tubing 20 through which the medication flows into the patient's body via an intravenous needle (not shown).

As described in the Background, a serious problem exists where a medical assistant removes the infusion set from pump 18 without first closing roller clamp 16, and as a result, free-flow (gravitational) of the medicinal fluid is established. Such incidents may be hazardous or even fatal depending on the medication and the patient's condition.

In accordance with the principles of the present invention, to avoid this danger, an automatic safety closure valve 22 is inserted between two sections of tubing 20, 23 below the pump 18, to insure that the free-flow condition cannot exist when the infusion set is removed from pump 18.

Referring now to Fig. 2, there is shown a cross- sectional side view of a preferred embodiment of automatic safety closure valve 22 operable with infusion system 10, in accordance with the principles of the present invention.

The automatic safety closure valve 22 comprises a double connector 24, with one end thereof connected to a standard infusion tube 20 of dimension 3.1 x 4 mm (e.g., a tube having an inner diameter of 3.1 mm and an outer diameter of 4 mm). At the other end, the connector 24 is connected to a standard infusion tube 23 of wider diameter (4.5 x 6 mm). On the end of connector 24 to which wider tube 23 is connected, there protrudes a rigid nozzle 26 having a length of 5-10 mm and dimensions 1.5 x 2.5 mm, which is integrally formed with connector 24 and is made of the same material (rigid PVC).

The end 28 of rigid nozzle 26 is formed with four ribs 29 and is sealed such that fluid cannot flow therethrough. Formed on the circumference of nozzle 26 are four holes 30 or slits. Fluid can flow through connector 24 via holes 30 from the thin tube 20 to the wider tube 23 (with inner diameter of 4.5 mm).

In accordance with the principles of the present invention, seated on rigid nozzle 26 is an elastic sleeve 32 of dimensions 2.2 x 3 mm, placed over its length between ribs 29 and connector 24. Ribs 29 prevent sleeve 32 from sliding off the end of nozzle 26 such that sleeve 32 covers the four holes 30, providing valve 22 with the ability to prevent fluid flow between thin tube 20 and wider tube 23. When there is a sufficient change in the fluid pressure, sleeve 32 of valve 22 expands, opening valve 22 as infusion pump 18 develops a pulsed fluid flow.

In the front end views of Figs. 3-5, the automatic safety closure valve 22 of Fig. 2 is shown, respectively, before assembly of valve 22 with elastic sleeve 32, after assembly of sleeve 32 on rigid nozzle 26 and during operation of valve 22. In Fig. 4, the elastic sleeve 32 is shown relaxed, and in Fig. 5, it is shown expanded as valve 22 opens under fluid pressure.

The difference in diameters between rigid nozzle 26 and elastic sleeve 32 is 0.3 mm, and this is one of the factors affecting the pressure required to open valve 22. The other two factors are the flexibility of elastic sleeve 32 and the size of the four holes 30. The elastic sleeve 32 may be manufactured of latex, silicone, or flexible PVC.

With regard to the three factors affecting the pressure required to open automatic safety closure valve 22, a design may be achieved in which the valve operates such that below a pressure of 1/4 atmosphere (2.9 PSI) fluid flow is blocked, and for a pressure greater than this, free-flow of fluid is permitted. When the user squeezes the outer tube (5 x 6.5 mm), this distorts elastic sleeve 32 and prevents it from sealing the four holes 30, to permit free-flow of fluid which enables the system to be primed before use. In order to ease the flow, the rigid nozzle 26 is tapered.

In operation, the inventive automatic safety closure valve 22 can distinguish between gravity flow and infusion pump 18 function. This is because valve 22 will not permit free-flow of fluid, while It will permit fluid flow delivered in pulses at a positive pressure higher than a set value. The maximum back pressure developed by valve 22 during pulsed operation of infusion pump 18 is 40-80 cm water. The back pressure of valve 22 is a function of the infusion rate at which pump 18 operates, the viscosity of the fluid, and the softness of elastic sleeve 32.

In Fig. 6, another embodiment of the automatic safety closure valve is shown, featuring a modified connector 40 for connecting infusion tubes 20 and 23. Connector 40 is sealed at a narrow end 42 and provided with four holes 30 as in the Fig. 2 emboidment. As shown in Fig. 7, the narrow end 42 of connector 40 is covered by a latex tube 44 (also known as a flash tube) which extends between connector 40 and a luer lock 46 used in IV administration sets. In this embodiment, latex tube 44 serves the same function as the elastic sleeve 32 of the Fig. 2 embodiment. In operation, latex tube 44 expands under pressure to open the valve and allow fluid flow through holes 30 of connector 40.

The alternative embodiment of Figs. 6-7 allows for greater simplification of the automatic safety closure valve arrangement. Since latex tube 44 is provided with European standard IV administration sets, the standard connector can simply be replaced with modified connector 40 as shown in Fig. 6.

Having described the invention with regard to certain specific embodiments, it is to be understood that the description is not meant as a limitation since further modifications may now suggest themselves to those skilled in the art, and it is intended to cover such modifications as fall within the scope of the appended claims. 18898clm.doc 13/10/97 108004/3

Claims

1. In a medical infusion system, an automatic safety closure valve comprising : means for connecting together at least two tubes for conducting fluids; and valve means associated with said connecting means, adapted to prevent free-flow of fluid therethrough below a predetermined fluid pressure, characterized in that said valve means is a bi-directional valve, and said valve is manually primable.

2. The valve of claim 1 wherein said predetermined fluid pressure is greater than that developed by gravity flow of fluid in the infusion system.

3. The valve of claim 1 wherein said predetermined fluid pressure is approximately 140mm mercury.

4. The valve of any of claims 1 - 3 wherein said valve means allows free-flow of fluid therethrough when said predetermined fluid pressure is exceeded.

5. The valve of any of claims 1 - 4 wherein said connecting means comprises a double-ended connector having a rigid nozzle extending from one end, said nozzle being sealed at its free end. and being formed with a plurality of openings disposed about its circumference said valve means comprising an elastic sleeve seated over said rigid nozzle and covering said openings.

6. The valve of claim 5 wherein said elastic sleeve is provided by one of said tubes for conducting fluid flow. 108004/3

7. The valve of claim 5 wherein said elastic sleeve is manufactured of latex.

8. The valve of claim 5 wherein said elastic sleeve is manufactured of silicone.

9. The valve of claim 5 wherein said elastic sleeve is manufactured of flexible PVC.

10. The valve of any of claims 1 - 9 wherein manipulation of said valve means distorts its shape and enables free-flow of fluid therethrough.

11. 1 1. The valve of any of claims 1 - 10 for use with an infusion pump which develops a fluid pressure which exceeds said predetermined fluid pressure during normal operation, and wherein upon removal of said fluid conducting tubes from said pump, said valve closes.

12. The valve of claim 11 wherein said fluid pressure is developed during pulsed fluid flow caused by said infusion pump.

13. A method of providing an automatic safety closure valve for a medical infusion system comprising the steps of: connecting together at least two tubes for conducting fluids; and providing bi-directional valve means associated with said connecting means, and manually priming said valve means by manipulation thereof to distort the shape and allow freeflow of liquid therethrough, wherein said providing step provides valve means for preventing free-flow of fluid therethrough below a predetermined fluid pressure. 2 ' 108004/2

14. The method of claim 13 wherein said predetermined fluid pressure is greater than that developed by gravity flow of fluid in the infusion system.

15. The method of claim 13 wherein said predetermined fluid pressure is approximately 140 mm mercury.

16. The method of any of claims 13-15 wherein said valve means allows free-flow of fluid therethrough when said predetermined fluid pressure is exceeded.

17. The method of any of claims 13-16 wherein said connecting step is performed by a double-ended connector having a rigid nozzle extending from one end, said nozzle being sealed at its free end, and being formed with a plurality of openings about its circumference, said valve means comprising an elastic sleeve seated over said rigid nozzle and covering said openings.

18. The method of claim 17 wherein said elastic sleeve is provided by one of said tubes for conducting fluid flow.

19. The method of any of claims 13-18 wherein manipulation-of said valve means distorts it shape and enables free-flow of fluid therethrough.

20. The method of any of claims 13-19 for use with an infusion pump which develops a fluid pressure which exceeds said predetermined fluid pressure during normal operation, and wherein upon removal of said fluid conducting tubes from said pump, said valve closes .

21. The method of claim 20 wherein said fluid pressure is developed during pulsed fluid flow caused by said infusion pump.

22. In a medical infusion system, an automatic safety closure valve substantially as described herein by way of example and with reference to the drawings.

23. In a medical infusion system, a method of providing an automatic safety closure valve substantially as described herein by way of example and with reference to the drawings.